Abstract: There is disclosed a magnetic recording medium in which a seed layer, under layer, intermediate layer, first magnetic layer, nonmagnetic layer, second magnetic layer, protective layer, and lubricant layer are successively laminated on a glass substrate, the nonmagnetic layer is constituted of an alloy containing Cr and C, and the magnetic layer is constituted of an alloy containing Co and Pt. The under layer includes at least the seed layer for finely dividing the crystal particles of the magnetic layer, the seed layer includes at least two or more layers of nonmagnetic films, and the intermediate layer formed of the material different from that of the nonmagnetic film is interposed between the nonmagnetic films. In measurement of the thermal stability of the magnetic recording medium, a head is used, the head includes a read/write element, and a write track width is twice or more as large as a read track width in the head.

Abstract: There is disclosed a magnetic recording medium in which a seed layer, under layer, intermediate layer, first magnetic layer, nonmagnetic layer, second magnetic layer, protective layer, and lubricant layer are successively laminated on a glass substrate, the nonmagnetic layer is constituted of an alloy containing Cr and C, and the magnetic layer is constituted of an alloy containing Co and Pt. The under layer includes at least the seed layer for finely dividing the crystal particles of the magnetic layer, the seed layer includes at least two or more layers of nonmagnetic films, and the intermediate layer formed of the material different from that of the nonmagnetic film is interposed between the nonmagnetic films. In measurement of the thermal stability of the magnetic recording medium, a head is used, the head includes a read/write element, and a write track width is twice or more as large as a read track width in the head.

Abstract: There is disclosed a magnetic recording medium in which a seed layer, under layer, intermediate layer, first magnetic layer, nonmagnetic layer, second magnetic layer, protective layer, and lubricant layer are successively laminated on a glass substrate, the nonmagnetic layer is constituted of an alloy containing Cr and C, and the magnetic layer is constituted of an alloy containing Co and Pt. The under layer includes at least the seed layer for finely dividing the crystal particles of the magnetic layer, the seed layer includes at least two or more layers of nonmagnetic films, and the intermediate layer formed of the material different from that of the nonmagnetic film is interposed between the nonmagnetic films. In measurement of the thermal stability of the magnetic recording medium, a head is used, the head includes a read/write element, and a write track width is twice or more as large as a read track width in the head.

Abstract: A substrate for an information recording medium has a microwaviness average height Ra? not greater than 0.05 microinch as measured by a contactless laser interference technique for measurement points within a measurement region of 50 ?m?-4 mm? on a surface of the substrate. The microwaviness average height Ra? is given by: Ra ? = 1 n ? ? i = 1 n ? ? | xi - x _ | , where xi represents a measurement point value of each measurement point, {overscore (x)} representing an average value of the measurement point values, n representing the number of said measurement points. Alternatively, the substrate has a waviness period between 300 ?m and 5 mm and a waviness average height Wa of 1.0 nm or less as measured by the contactless laser interference technique for measurement points in a measurement region surrounded by two concentric circles which is spaced from a center of a surface of the substrate by a predetermined distance.

Abstract: A substrate for an information recording medium has a microwaviness average height Ra′ not greater than 0.05 microinch as measured by a contactless laser interference technique for measurement points within a measurement region of 50 &mgr;m□-4 mm□ on a surface of the substrate.

Abstract: A substrate for an information recording medium has a microwaviness average height Ra′ not greater than 0.05 microinch as measured by a contactless laser interference technique for measurement points within a measurement region of 50 &mgr;m□-4 mm□ on a surface of the substrate.